Fx dreamline huma reg question

I’ve had my dreamline for about 3 years, any ways while I did a complete rebuild of the huma reg extra high pressure all new orings and also the oring down in the bottle adapter. When I started to fill the gun I had the reg all the way tight not like I wrenched on it but snug tight anyways the reg pressure is the same as bottle pressure and it leaks from the atmosphere port! Everything was lubed with silicone too. Any idea what’s going on?
 
If I am remembering correctly there is an oring in the the reg hole. It is recessed in a groove and very hard to see. It is there to seal on the outside diameter of the regulator where I marked on this photo. I think it was my Dreamline that had this o’ring but not absolutely sure.

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